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#1 |
Registered User
Join Date: Jun 2018
Location: Munising,Mi
Posts: 360
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91 Suburban Tranny
I have a chance to get a Free suburban auto tranny and transfer case .
in fact I can have the whole truck. My question n. will the tranny/transfer case fit my 68 K1500 4x4 GMC truck ok ? will the radiator fit ? |
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#2 |
Registered User
Join Date: Mar 2014
Location: Corvallis, OR
Posts: 712
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Re: 91 Suburban Tranny
91 Suburban's came with 3 different automatic transmission options. 700R4, Turbo400 and 4L80E. All of these should fit, but may require a significant amount of work to get them in.
The radiator core is about the same size and the inlet/outlet is in the right place. You may need to modify the mounts, but it should fit in the hole.
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1972 GMC Jimmy Custom 4.8L (L20)/6L90E/NP205 1989 Chevy Suburban V2500 350/Turbo 400/4.11 gears 1996 Chevy Suburban K1500 350/4L60E |
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#3 | |
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Join Date: Jun 2018
Location: Munising,Mi
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Re: 91 Suburban Tranny
Quote:
You say a significant amount of work to install ? Can you give me a idea on what it would take ? I already have a manual tranny with the transfer case ( Rockwell ) , I would have thought it would be pretty close to a simple swap out ? I was original just going to put in a 700R4 period but this offer came along , so that’s the way I would like to go . I’m actually wanting the automatic for the hilly city streets we drive on around the country. Kind of hard with a stick when you have cars behind you on a steep grade . Last edited by mygmctruck1; 07-09-2018 at 08:26 AM. |
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#4 |
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Join Date: Dec 1999
Location: Austin, TX, USA
Posts: 7,717
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Re: 91 Suburban Tranny
If it was the 4L80 that would be a score.
Is it a half ton? I have taken apart two different K20 subs to donate axles to Jimmy projects. 84 TH700 with 3.73 and an 86 that was TH400 with 4.10. You can use the front axle to convert yours to disc brakes but if gears don't match what you have, you will have to regear one end.
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44 Willys MB 52 M38A1 64 Corvette Coupe 68 Camaro 'vert LT1 & TH700 69 Z/28 355 12.6's @110 69 Chevy Short Step 4 1/2"/7" drop 72 Jimmy 4WD 4spd 4" & 35's 02 GMC 2500HD 4x4 Duramax |
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#5 | |
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Join Date: Jun 2018
Location: Munising,Mi
Posts: 360
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Re: 91 Suburban Tranny
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I was hoping to keep the truck old school , much easier to work on for me. This spring we went on a road rally , one of our friends has a 57 Chevy with modern fuel injection , tranny etc. he was having trouble the whole week we were out . Even though he had a reader , he still couldn’t get it right . |
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#6 |
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Join Date: Mar 2014
Location: Corvallis, OR
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Re: 91 Suburban Tranny
It isn't a huge deal to swap it out for either one if you use the transfer case from the 91 Suburban. Probably the easiest thing to do is to keep the engine in the same place and allow the transfer case to move back. You will need to move the crossmember back and find or make a suitable mount to hold everything. The later transfer cases are a lot lighter and don't require the side mount or torque strut that was used.
You will also need to shorten the rear drive shaft. You might be able to get away with using the front driveshaft off the suburban. Exhaust might have to be modified. You may need to make a new shifter for the transfer case to get it to come up through the factory hole. The transmission will also need a cooler, so this will have to be added. If the suburban is a 3/4 ton with overdrive it should be a 4L80. If it's a 1/2 ton, then it's a 700R4. Using the 4L80E will require either using the factory computer (wouldn't recommend), or to buy an aftermarket computer for around $500. The only external sensor these need are a throttle position sensor ~$40. Swapping in a 700R4 will require the TV cable. Since it is behind a TBI suburban I suspect none of the bracketry will fit on your truck. If it's an early 4L60 (I don't believe any square body suburban's came with one) then the same controller and TPS would be required to make it work.
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1972 GMC Jimmy Custom 4.8L (L20)/6L90E/NP205 1989 Chevy Suburban V2500 350/Turbo 400/4.11 gears 1996 Chevy Suburban K1500 350/4L60E |
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#7 |
Registered User
Join Date: Jun 2018
Location: Munising,Mi
Posts: 360
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Re: 91 Suburban Tranny
Just ran into a snag regarding the suburban tranny/trans case. My front pumpkin ,drive shaft is on the pass side. The suburban is on the drivers side . Which means , I would need to also use his front axle set up. For me not an option , unless the transfer case can be rotated 180 degrees ?
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#8 |
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Join Date: Apr 2011
Location: Klein Texas
Posts: 3,852
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Re: 91 Suburban Tranny
Are you sure of the model year? 1991 Suburban should be a square body and IIRC are passenger side drops
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My Classics: '72 K20 Suburban + '65 Dodge Town Wagon '72 Corvette Roadster +'67 Corvette Roadster '73 Z-28 Camaro '63 Ford SWB Uni Pickup '50 Ford Coupe |
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#9 |
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Re: 91 Suburban Tranny
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#10 | |||
"I ain't nobody, dork."
Join Date: Sep 2007
Location: Whidbey Island, Washington
Posts: 8,936
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Re: 91 Suburban Tranny
I had a 1991 Suburban 3/4 ton with a 4L80E in it. Wish I still had that rig to thgis day.
Quote:
Gsry
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'cuz chicks dig scars... My 1972 GMC 1500 Super Custom (Creeping Death) "long term" build thread. The Rebuild of Creeping Death after the wreck Quote:
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#11 |
Senior Member
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Location: Oak Harbor, WA
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Re: 91 Suburban Tranny
Well.....if it's a 92, that is a zero percent chance it will work for the front as you know it IFS.
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#12 |
Proprietor of Dale's Corner
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Re: 91 Suburban Tranny
It would have to be a 92 to have a drivers side drop. This also means its an independent front end.
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#13 |
Registered User
Join Date: Jun 2018
Location: Munising,Mi
Posts: 360
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Re: 91 Suburban Tranny
Ok , found out the suburban is a 92 , drivers side front drive shaft. Can I get a transfercase with a pass side shaft ? The tranny is a 700 r for sure.
It’s free and it sure would be nice to use it . |
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#14 |
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Join Date: Dec 1999
Location: Austin, TX, USA
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Re: 91 Suburban Tranny
You can adapt it to your transfercase. That's a $500 proposition though. There is no cheap way to do an OD swap in a 4x4.
You could get a TH700 or 4L80 from a 91 or earlier truck and adapt to your t-case. Or you could run it with the case it came with. Both solutions would require new driveshafts. Do you have an integral or divorced t-case in your truck now? You could keep a divorced case and use a 2x4 trans, but none of the scenarios play out "cheap and easy" with the '92 donor.
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44 Willys MB 52 M38A1 64 Corvette Coupe 68 Camaro 'vert LT1 & TH700 69 Z/28 355 12.6's @110 69 Chevy Short Step 4 1/2"/7" drop 72 Jimmy 4WD 4spd 4" & 35's 02 GMC 2500HD 4x4 Duramax |
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#15 | |
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Join Date: Jun 2018
Location: Munising,Mi
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Re: 91 Suburban Tranny
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#16 |
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Join Date: Apr 2011
Location: Klein Texas
Posts: 3,852
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Re: 91 Suburban Tranny
You can do a search on this site for TH700 or 4L60 and find out what it takes to fit.
I used an advanced adapter output shaft to mate a 4L60 to my NP205. I moved the engine mounts ~1.5 inches forward. I had to lengthen the exhaust, shorten the coolant hoses, move the shift linkage and install a different fan shroud. I like the driving experience but but isn't a easy direct swap.
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#17 |
Registered User
Join Date: Jun 2018
Location: Munising,Mi
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Re: 91 Suburban Tranny
What I am really looking to do is use the 700r for a 4x4 and get a transfercase designed for that tranny and a drivers side Shaft.
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#18 |
Registered User
Join Date: Dec 1999
Location: Austin, TX, USA
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Re: 91 Suburban Tranny
I have an '84 square body suburban and it has a TH700R4 in it and what I would assume is a NP208 t-case. Not sure on that. So they are out there. You need to source from a square body solid axle truck though. Suburbans are usually the best (cheapest!) donor.
Your truck would have come with a Rockwell T-case originally and you won't find any adapters for one of those to a TH700.
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44 Willys MB 52 M38A1 64 Corvette Coupe 68 Camaro 'vert LT1 & TH700 69 Z/28 355 12.6's @110 69 Chevy Short Step 4 1/2"/7" drop 72 Jimmy 4WD 4spd 4" & 35's 02 GMC 2500HD 4x4 Duramax |
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#19 | |
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Join Date: Jun 2018
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Re: 91 Suburban Tranny
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